Automotive upholstery applications, excluding seating applications, very often employ a soft, relatively thin textile or leather cover positioned over a substrate material constructed from a less flexible material, such as metal, plastic, foam, or the like. Automotive seating applications, being a specialized subset of automotive upholstery applications, typically comprise an inner substrate constructed from a resilient foam material overlain by the aforesaid soft cover. In either automotive upholstery application, the soft cover is usually formed from a number of parts stitched to each other by seams along join lines. In automotive seating applications, the threads of the seams are often adapted to attach to portions of the foam substrate material below, thereby holding the cover in a fixed position with respect to the foam substrate material. In non-seating applications, the soft cover may be attached by other more conventional attachment means, such as, for example, adhesives, clips, staples and the like.
The seam construction on automotive upholstery arrangements is typically carried out using either a Deck seam construction, or a French seam construction. An example of a Deck seam construction 15 is shown in FIG. 1. As shown therein, adjacent cover parts 17 and 19 are aligned along an edge 21 of each cover part, and placed with the outer surfaces of each cover part in mutual abutting contact. An overlapping margin region is thereby defined, and a first stitch line 23 applied, generally spaced from, and extending generally parallel to the aligned edge. This arrangement creates two seam flaps 25 and 27 which are then folded underneath one of the cover parts 19, and a second stitch line 29 is applied with the overlapping margin region and transverse to a top surface of the cover parts, to affix the seam flaps 25 and 27 underneath one of the cover parts 19. Thus, a two-part seam creation process is required, wherein the first stitch line 23 joins two adjacent cover parts 17 and 19, and a subsequently applied stitch line 29 adjoins the seam flaps 25 and 27 underneath one of the cover parts 19, providing a decorative finish to the seam construction.
An example of a French seam construction 30 is shown in FIG. 2. As seen therein, a French seam construction 30 is similar to the Deck seam construction 15, except that respective seam flaps 32 and 34 are folded underneath corresponding cover parts 36 and 38 (i.e., the flaps are folded in opposite directions). A first stitch line 40 is used to join the cover parts 35 and 38. Second 42 and third 44 stitch lines are subsequently applied to affix the respective seam flaps 32 and 34 to the corresponding cover parts 36 and 38. Thus, there is one join stitch line 40 and two decorative stitch lines 42 and 44 adjoining the folded over seam flaps 32 and 34 of each cover part 36 and 38 to a bottom surface of the respective cover part 36 or 38.
Both the Deck, and French seam constructions require two separate and distinct operations to complete the seam. That is, in the first operation, join stitching is applied to join the adjacent cover portions, and in a subsequent operation, a decorative stitching is applied to fix the underlying seam flap to one, or both of the cover parts. The decorative stitching may be applied in a pattern, or with a coloured thread, which provides for a finished look to the seam construction.
Both the Deck, and French seam constructions typically have excess material (known as “salvage”) positioned on the underside of the cover material, which salvage is necessary to allow for proper stitching at the seams. This being the case, in order to ensure that a French or Deck seam lies flat and uniform across the upper surface of the cover, a ditch must be formed in the underlying rigid substrate material on which the upholstery cover is being applied to accommodate the thickness of the salvage material. In other words, such a ditch must be formed in the substrate material to ensure that the Deck or French seam remains flush with the remainder of the upholstery cover. This adds to the cost and complexity of producing a covered upholstery trim piece of the type discussed above. Moreover, this is particularly problematic where both an uncovered and a covered upholstery trim option are offered by a vehicle manufacturer to its customers, as both types of substrate materials (i.e. with a ditch and without) must be readily available in the production inventory of parts.
There is thus a need in the art for an automotive upholstery seam construction which can be applied in a single operation, and without the need for manipulating portions of the cover parts, such as by folding or otherwise rotating the cover parts. There is also a need in the art for a seam construction which does not require further manipulation of substrate materials to accommodate laying flat of the seam construction over the substrate material. There is a further need in the art for a seam construction which produces less waste material (i.e., salvage), as is created by the need for one or more seam flaps as required to form a Deck or French seam. Additionally, there is a need in the art for a seam construction that utilizes a multiple needle interacted process, thereby reducing the number of operations necessary to form the join seam and decoration seam.
In attaching the upholstery cover to a foam substrate material, such as in automotive seating applications, a fixing element is sometimes formed with, or formed to interact with, the seam construction, and thereby prevents the upholstery cover from shifting with respect to the substrate material. One such construction and fixing element is described in U.S. Pat. No. 6,561,581 issued on May 13, 2003 to Michot et al. FIGS. 5 to 7 of Michot et al. show a hook device arranged on a tape, which is secured to the foam substrate material at a position arranged to coincide with the seam construction of the seat cover. The hook device has a lobed end which engages the stitching of the seam construction and thus prevents relative movement between the seat cover and the foam substrate material. In forming the stitching of the Deck seam construction, additional stitch lines are provided on the seam flap, having a loop portion which can be adapted to engage the hook device.
There is also a need in the art for a simplified seam construction, which can have integrated therewith a fixing element for interaction with an underlying substrate material, such as in automotive seating applications, or which can interact with a fixing element positioned on the foam substrate material.
There is a further need in the art for a seam construction which can be applied easily and in a single operation to join adjacent cover parts and any additional elements to be integrated with the seam, such as those used for decoration, or for engaging with the substrate material.